Flow ratio blocker valve for air suspension



June 7, 1960 R. w. GRAHAM 2,939,725 mow RATIO BLocxR VALVE Fox AIR SUSPENSION Filed April so, l195s PWLEVEL/NG 2,939,725 Patented June 7, 1960.

FLOW RATO BLOCKER `'VALVE FOR AIR SUSPENSION Robert W. Graham, Birmingham, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporal-V tion of Delaware Enea Ape-30,1958, senNs. 731,934-

12 Claims. (onzen-124) Y This invention relates, to vehicle airsuspeusionsystems and morefparticularly toautomatic flow control apparatus for use in associationwith air suspension systems.

In.` copending application Serial No. 606,155, now Ratent No. 2,848,249, dated Aug. 19, 1958, Joseph F. Bertsch et al., assignedto GeneralMotors.Corporation, it has beeny proposed to-pro`vide an air suspension system incorporating an, orilice `controlled diaphragm .actuated blocker. valve assemblyA whichI operates to substantially eliminate air consumptionfofthe system whenever the attitude of the vehicle is suchithat simultaneous intakeof air toone spring and exhaust from another wouldnormally occur. In this system, one diaphragm assembly operates `as a function of pressure drop resulting from exhaust ilow` tofautomatically block the, normal flow path of, air in the intake side of the system, while a secondsdiaphragm assembly 'operates asa function of pressure,` drop) resultingjfromintake ow to automatically tends to move the blocker valve from a neutral position blocking both` intake and exhaust ilow to a position blocking only intake flow, While intake pressure drop tends to move the blocker valve from the neutral position to a position blocking only exhaust flow, wherein the blocker assembly is formed so that less pressure drop is required to restore the valve to neutral than to move it to either unblocking position.

These and other objects, advantages, and features of the invention Willbecorne more fully apparent as referl ence is had to the accompanying specilication and drawthe intake and exhaust cireuits is limited to theamount passing through the associated orice.

y Anobject ofthe present invention is to `provide an improvedair suspension system. i f- `Another object is to ,providev animproved blocker valve assembly for `vehicleair` suspension. i f A further Objectis to `provide an ar suspension system including iiow control apparatus ,which operates `as a` function of llow ratio between intakelowi and exhaust llow of airl in the system to control. the` rate-of leveling ofthe vehicle under various conditionsof vehicle attitude.

,Still another object ist` to provide an improvedorice control blocker valve assembly for air suspension systems. Still a further object is to provide` a dual diaphragm air flow control apparatus Which automatically regulates operation of a conventionalleveling systemso as toprof vide relatively limited flow of air when the ratio of'` air flow to and from the air springs is, approximately equal and to provide marked increase of intake or exhaust air flow` rate when the flow ratio becomes` unequal.

A still further object is to provide a device ofthetype i described which operates responsive to pressureV drop occurring asa result ofair flow in the intake and exhaust sides offthe system.

Still another object isV 'to'.provide sa, device ofthe stated ,character including a valve assembly which presentsa substantially greater'elective area when acted upon by pressure dropgtending. to move the device` to blocking position than the, effective area acted upon by pressure tending tqmove thedeViCe. to. unblockingposition. v

Yeta further obJ'eQct is to provide a flow ratio sensi.-

tive blocker `,valve assembly for an air, suspension system includinga iirst diaphragm assembly actuated responsive ing wherein:

Fig. l is an elevational view in section showing the, improved blocker valve assembly.

Fig. 2 is a diagrammatic sketch illustrating an air s uspension system incorporating the invention.

In the drawing, the reference numeral 2 designates generally a valve body which is adapted for dispositionlin the main iluid circuit of any conventional air suspension system, as for example` the type shown in copendingapplication Serial No. 606,155, previously. referred`,to. Valve body 2 is connected in communicatingrelation with high pressure tank 3 by a conduit 4 and with al low pressure tank 5 by a conduit 6. At its opposite side, valve body 2 is connected in communicating Vrelation with the intake and exhaust sides respectively of air spring level ing valves 7, 9 and `lit by conduits 8, lll, l2gand1j4; 16, 1S.

In the` illustrated embodiment, valve rbody 2 comprises an upper, center, and lower section 26, 22, and 24, re: spectively, which are assembled in vertical stackedkrelation. Sections 2o Vand 2d are each providedwith, opppv sitely` directed cavities 2.6 and 2l'whicb cooperate with the upper and lower faces Sil and 32. of centerisection 2.2 to provide pressure chambers 34 and` 36. Clampedbetween `the abutting faces of sections 20` and ZZ is a` ilexible diaphragm 33, while ,zt-second flexible diaphragmfll) is clampedfbetween the abutting faces of section- 22`and section Guided in a central vertical bore 42 in section 22, is the stern portion da of a valve assembly 46, ,the opposite ends of which have connected thereto cup-,shaped circular members 4S and 5i? which abut the respective inner faces of diaphragms 38 and 4l?. `Arranged concentrically around circular members 48 and Sil and guided in annular recesses 52 and 54- of section 22j area pair of flanged annular ring` elements 56 and 5b having radial flanges 60 and 62, which underlie and abut the inner faces` of diaphragme 38 and lit. Elements 56 and S8 are provided with radially inwardly extending tangs 6d` and 66 which overlie the outer peripheries of cup-shaped meme bers 4S and E'll so that the latter are free to moveV in: wardly independently, but upon outward movement from `the position shown in the drawing cause ring members 56 and 5S to move therewith.

Aligned with stem Lid. and secured in any suitable manner on the outer face of each diaphragm 33, and 40. are. a pair of elastomeric pads 68. and 76 respectively. The overall lengthof stem de and pads 6 -3 and 7i) is selected so that the end face of eachpad normally` exerts apres determined yielding pressure on lthe adiacent end.` face of the adjacent central boss portion 72 and 74 oflsections 2li and 24, respectively, for a purpose shortly robe described. e e

VFormed interiorly of` section 24 and communicating with intake conduit 4 is a passage 78 which opens into cavity 2b. A branch passage Si? extends upwardly from passage 73 and communicates with an axially aligned portion of a passage 82 formed `in section 22. Disposed at the juncture of passages Sil and 82 in the plane of diaphragm di? is a metering orifice 84, the purpose of, which` will be described shortly. Passage S2, extends transversely through section 22 and opens into the annular recess 4' formed therein. At its opposite side, section 22 is formed With a second transverse passage -85 having a depending vertical Vportion 86 which is aligned witha vertical passage 88 formed in lower section 24. Extending downwardly through boss portion 74 are three vertical passages 90, 92, and 94 having transversely extending portions rwhich communicate respectively with conduits 10, 8 and 12rleading to the intake sides of the leveling valves, not shown. -In addition to the direct connection with the relatively large bore passages 90, 92, and 94, conduits 8, 10, and 12 are arranged in communication with passage 88 by means of small bore passages 96, 98, and 100.

Upper section 20 in turn is provided with three transverse passages 102, 104, and 106 which are connected to exhaust conduits 14, 16,.. and 18, respectively. At their inner ends, passages 102, 104, and 106 extend downwardly through boss 72 and open into cavity 26. In addisage 118, the inner end of which opens into annular recess 52,'Whi1e the outer end is connected to conduit 6 leading to the low pressure tank. Formed in the wall 120 of upper section 20 is an orifice 122 which provides direct communication between cavity 26 and passage 114.

In operation, the device just described functions in the following manner. When'the vehicle is in the normal level attitude, such that the flow of air to the springs equals the flow of air from the springs, closures 68 and I ,70 remain in the position shown in the drawings thereby blocking movement of air from conduit 4 through pasherently tolerates normal manufacturing sages 90, 92, and 94 to intake conduits 8, 10, and 12 and from exhaust conduits 14, 16, and 18 through passages 102, 104, and 106 to conduit 4. While'the pressure in the intake conduits will normally be greater than the pressure in the exhaust conduits, the pressure dilferential is counter .balancedY by coil spring 124 disposed between cup150 and the base of section 22. Accordingly, movementl of air from the leveling valvesA to the low pressure tank must ow through small bore passages .108, 110, and 112, while movement of air to the leveling valves from the high pressure tank must ow through small Ybore passages 96, 98, and 1100. Y As long as intake and exhaust flow rate occurs at substantially a 1:1 ratio (ow inzflow out), pressure drop measured across intake orifice 84 and exe haust orice' 122 will be substantially equal and the' position of diaphragms 38 and 40 will remain unaffected. However, if a load, however slight, is added or removed from the sprung portion of the vehicle, the ow ratio approaches zero or infinity since one of the factors of the ratio will equal zero flow. For example, if a load is applied, the ow ratio will Ybecome much larger than 1:1, While removal of load will produce a much smaller ratio than 1:1. In the lirst instance, closure 70 will be unseated providing direct communication between passage 78 and each of passages 90, 92, and 94 thereby permitting fast ow of air to the leveling valves. In the second instance, the closure 68 is unseated providing direct communication between passages 102, 104, and 106 and passage 118 leading to the low pressure tank thereby'allowing rapid exhaust of air from the leveling valves. In each instance, it will be noted that unseating of one closure results in increased closing pressure on the other closure by virtue of the interconnecting stem 44. This axial displacement of stem 44 causes one of the cupshaped members 48 and 50 to be moved inwardly with respect to center section 22, While the other is moved outwardly relative thereto. Taking, for example, the condition occurring uponunseating of closure 70, it will be 2,939,725 .y Y 'i in;

seen that cup-shaped member 50 moves toward center section 22, while cup-shaped member 48 moves away from center section 22. Because of the one-way overlapping relationship of ring member-56, the latter Vis also moved upwardly with member 48. As a result, as soon as fast flow leveling induces overshooting, the exhaust side of each leveling valve immediately opens, creating a marked pressure drop measured across orifice 122. Upon this occurrence, even ,though the pressureV drop across orice 122 may not be as great as the pressure. drop already occurring across orifice 84 as a result of fast intake ilow, closure 70'w'ill be snappedto closed position due tothe fact that the area acted upon by diaphragm 38 is greater Vthan the areav acted upon by diaphragm 40. In the case just described, the area acted upon by diaphragm 40 to unseat closure 70 is equal to the elective area of cup-shaped member 50, while the elective area acted upon by diaphragm '38 to return closure 70 to blocking positionl is the sum of the areas of cupshaped member 48 and the radial flange 60 of ring element S6. As will be noted fromY the drawing, the added area provided byflange 60 or 62 is effective only in restoring the valve assembly to the neutral blocking position since further inward movement of the ring is arrested by engagement with the face of center section 22. It will now be seen that a greater pressure drop isalways required to unseat .eitherclosure 68 or 70 than is required to keep it seated. As a result, the valve assembly seeks a quiescent state of ow of air to and from the leveling valves which tends to prevent hunting due to time lag, floating conditions produced by undulating roads, and other moderate disturbances. In addition, the device in*-` variations in orifice sizes, elfective areas, etc. While but one embodiment of theinvention has been shown and. described, it will be apparent that other changes and modiicationsgm'a'y be made therein. It is, therefore, understood that it is not intended to limit the invention tothe embodiment shown, but only by the scope of the claims which follow.

I claim: Y l y f 1. Control means for apneumatic suspensionsystem having a source of air pressure, means-for exhausting receiving air from said source vand having an outlet to said i air' from the system; a plurality of air springs in the cirf cuit between saidVs/ourcei and said exhaust means, said circuit including a pressure line from said'source to each spring, and an exhaust line from each spring to said exhaust means, said control means comprising a master valve through which all air from said source and to said exhaust'means liows, said master valve including a pressure section and an exhaust section, said pressure section receiving air from said source and having an outlet to said springs incorporating normally closed passage means and a by-pass restriction orifice, said exhaust section re ceivng air from said springs and having an outlet to said exhaust means incorporating similar normally closed passage means and restriction oriice, each of said sections including elements actuated by pressure drop across the corresponding restriction orifice to open the associated normally closed passage thereby increasing the flow rate to orrfrom the springs.

2. Control means for a pneumatic suspension system having a source of air pressure, means for exhausting air from the system, a plurality of air springs in the circuit between said source and said exhaust means, said cirf cuit including a pressure line from said source to each spring, and an exhaust line from each spring to said exhaust means, said control means comprising amaster' valve through which 4all air from said source and to said exhaust means flows, s aid master valve including a pressure section and an exhaust section, said pressure section springs incorporating normally closed passage means and a by-'pass restriction orifice, said exhaust section receiving haust meiis'incorporati'igrsiniilar normallyclbsed passage means andre'sttictionsorili'ce, each ,ofi said sections @ladina 21eme atuatcsby pressure drop across the wrrespcndis rstricticaorice reopen the associated nurin ially;A closed passage thereby increasing thefifiow rate to or from the springs, said elements being positively interconnected so that opening of one normally closed passage prevents concurrent opening of the other normally closed passage.

3. Control means for a pneumatic suspension system having a source of air pressure, means for exhausting air from the system, a plurality of air springs in the circuit between said source and said exhaust means, said circuit including a pressure line from said source to each spring, and an exhaust line from each spring to said exhaust means, said control means comprising a master valve through which all air from said source and to said exhaust means flows, said master valve including a pressure section and an exhaust section, said pressure section receiving air from said source and having an outlet to said springs incorporating normally closed passage means and a by-pass restriction or-ice, said exhaust section receiving air from said springs and having an outlet to said exhaust means incorporating similar normally closed passage means and restriction orifice, each of said sections including diaphragm operated elements actuated by pressure drop across the corresponding restriction orifice to open the associated normally closed passage thereby increasing the ow rate to or from the springs, said elements being positively interconnected so that opening of one normally closed passage prevents concurrent opening of the other normally closed passage.

4. Control means for a pneumatic suspension system having a source of air pressure, means for exhausting -air from the system, a plurality of air springs in the circuit between said source and said exhaust means, said circuit including a pressure line from said source to each spring, and an exhaust line from each spring to said exhaust means, said control means comprising a master valve through which all air from said source and to'said `exhaust means ows, said master valve including a pressure section and an exhaust section, said pressure section receiving air from said source and having an outlet to said springs incorporating normally closed passage means and a by-pass restriction orifice, said exhaust section receiving air from said springs and having an outlet to said exhaust means incorporatnig similar normally closed passage means and restriction orifice, each of said sections including diaphragm operated elements actuated by pressure drop across the corresponding restriction orifice to open the associated normally closed passage thereby increasing the ow rate to or from the springs, said elements being positively interconnected so that opening of one normally closed passage prevents concurrent opening of the other normally closed passage, and means associated with each of said interconnected i elements causing the latter to be differentially responsive tion than the pressure drop required across the other oriiice to return the element to closed position.

5. In a pneumatic suspension system of the type including a plurality of air springs, a high pressure circuit, an exhaust circuit, and height responsive leveling means for introducing and exhausting air from the springs, flow control apparatus comprising a master valve through which all pressure and exhaust air ilow, said mastervalve including a pressure section and an exhaustsection, a iiexible diaphragm partition for each of said sections, pressure inlet means communicating directly with one side of said pressure section, an orifice providing restricted communication between said inlet and the other side of said section, exhaust outlet means communicating directly with one side of said exhaust section, an orifice providing 'restricted communication between the other side of said section and saidlou'tlet, pressure-outlet means" to. said springsl arranged to communicate with both sides of said pressure section, exhaust inletmeans from s aidl springs arranged to communicate with both"V sides offsaidtexhaust section, and a` pressure responsivevalve as semblydis'- posed between said sections includingclosuremeans normally blocking communication between the respective outlet and inlet means of said pressure and exhaust sections with the respective sides of said pressure and exhaust sections having direct communication with said pressure inlet means and said exhaust outlet means, said valve assembly being actuated in one direction by pressure drop across the restriction orice in the pressure section and in the other direction by pressure drop across the restriction orifice in the exhaust section.

6. The invention claimed in claim 5 wherein said closure means is capable of absorbing substantial compressirve deformation.

7. In a device of the class described, a valve body hav'- ing a pair of spaced cavities, a exible diaphragm partition in each cavity, a plunger slidably disposed in said body between said diaphragms, a piston connected at either end of said plunger abutting the adjacent diaphragm, closure means at either end of each plunger normally biasing the latter to a neutral central position, and an auxiliary member associated with each piston in one-way overlapping engagement whereby pressure exerted on either diaphragm displaces the adjacent piston inwardly independently of its associated auxiliary member, and the other piston outwardly concurrently with its associated member.

8. In a device of the class described, a valve body having a pair of spaced cavities, a exible diaphragm partition in each cavity, a plunger slidably disposed in said body between said diaphragms, a piston connected at either end of saidplunger abutting the adjacent diaphragm, closure means secured to each diaphragm at either end of each plunger normally biasing the latter to a neutral central position, and an auxiliary member associated with each piston in one-way overlapping engagement whereby pressure exerted on either diaphragm displaces the adjacent piston inwardly independently of `its associated auxiliary member, and the other piston outwardly concurrently with its associated member. 9. In a device of the class described, a valve body having a pair of spaced cavities, a flexible diaphragm parttion in each cavity, a plunger slidably disposed in said body between said diaphragms, a circular piston connected at either end of said plunger abutting the adjacent diaphragm, closure means secured to each diaphragm at either end of each plunger normally biasing the latter to a neutral central position, and an auxiliary member associated with each piston in one-way overlapping engagement whereby pressure exerted on either diaphragm displaces the adjacent piston inwardly independently of its associated auxiliary member, and the other piston outwardly concurrently with its associated member.

10. In a device of the class described, a valve body having a pair of spaced cavities, a flexible diaphragm partition in each cavity, a plunger slidably disposed in said body between said diaphragms, a circular piston connected at either end of said plunger abutting the adjacent dia-r phragm, closure means secured to each diaphragm lat, t

either end of each plunger normally biasing the latter to a neutral central position, and an annular auxiliary -member associated with each piston in one-way overlapping engagement whereby pressure exerted on either diaphragm displaces the adjacent piston inwardly independently of its associated auxiliary member, and the other piston outwardly concurrently with its associate auxiliary member.

l1. lThe structure set forth in` claim 7 wherein said auxiliary members in outwardly displaced position in- 

